Richard Venancio

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.
Supose you have a big main menu, and this have a lot submenus, so, to show yours submenus in a side of your site, you create one new menu in wordpress for each submenu you have, and create codes to define which submenu you show, according the location in hierarchy’s menu you are.
This is very tiring and biggest, for just show the submenu, then this plugin do all things for you, but don’t create any menu, it just get the submenu according the main menu.

RVSubMenu

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.

Willy Bahuaud

It add fields to nav menu items in the menu editor (on admin side), allowing to automatically generate submenus on front-end.
You can, for example, ask that the last 5 items of a category appear in the sub-menu. You can also request to display all sub-terms of a taxonomy term. Or you can also ask to list all the contents associated with a CPT archive page…

Auto Generate Submenus

It's easy to add content and automatically appears in the menu, thanks to this plugin

Great plugin!

With this plugin, you can add an automatically generated submenu for each menu item.

RVSubMenu vs Auto Generate Submenus